DNA methylation profile of genes involved in inflammation and autoimmunity correlates with vascular function in morbidly obese adults

Abstract

We thank the editor and the reviewers for their thoughtful review of our manuscript and for the opportunity to improve and resubmit. The detailed comments the authors received are indeed beneficial and improve the quality of our data presentation and interpretation. We have responded to the reviewers' comments/critiques below and have incorporated the recommended changes in the manuscript. Major concernsComment # 1: Do you have information on dietary preferences in your sample? Are there omnivores, vegetarian or vegans? This is important due to the potential use of vitamin supplements with vitamin B12. The authors did not discuss the differences in folate and vitamin B12 between controls and subjects with obesity, and how this is related with the observed methylation patterns… this should be addressed due to its one of the strengths of this study. Response to comment # 1:We agree with the reviewer and we obtained questionnaires about supplementations however, most subjects were not able to recall taking supplements that specifically rich in folate or vitamin B12. Accordingly, we decided to measure actual concentrations of folate and B12 in plasma. Also, we do not have specific information about dietary preferences of our subjects but realizing the importance of this information, we will start to implement this questionnaire in our future studies. We also agree that the part about vitamin B12 and folate in obese and non-obese subjects and the relation to methylation was missing in the discussion. Per your recommendation, we added a new paragraph that discusses this part (lines 341-360).Comment # 2: The data in table 2 was analyzed by sex? Considering that HDL-C cut-off is different among men and women…Response to comment # 2: Results for HDL-C did not show significant differences between males and females within each group (obese and non-obese). When compared, the p value was higher than 0.7 in both groups. Comment # 3:The authors show interesting data in Table 2, where HOMA index and FPI is higher in obese subjects in comparison to controls, however, FPG and HbA1c are not different among groups as expected. Please discuss about these result.Response to comment # 3: Insulin can be higher in obese individuals which results in higher HOMA-IR at earlier stages of insulin resistance before the conditions mature to full-blown diabetes where glucose metabolism is actually compromised and manifested as high blood glucose. We believe that some of subjects in the obese group are at early stages of insulin resistance but since they are young (mid 30s in average), a complete picture of diabetes might not have been developed yet. A statement that explain this was added to the discussion (lines 260-263)Comment # 4: Alcohol consumption was measured by a questionnaire, is this validated? This information is not described in methods, fix this issue. In table 2 the data appears as "alcohol drinkers %", however, in the discussion, the authors mentioned that they have classified into none, mild, moderate and heavy drinking, but this...

An Overview of Epigenetics in Obesity: The Role of Lifestyle and Therapeutic Interventions

“…On top of these genes is HIF3A (hypoxia-inducible factor 3a), which is an essential gene in metabolic and physiological responses to hypoxia whose methylation has been linked to obesity in both adults and children [25,26]. In addition, genes involved in inflammation and oxidative stress such as TNF (tumor necrosis factor), IL6 (interleukin 6), and TFAM (mitochondrial transcription factor A) exhibited aberrant DNA methylation in obese individuals and correlated with abnormal expression and disturbed function of these genes [27][28][29]. Collectively, obesity has been linked to altered DNA methylation patterns, which could serve as biomarkers and therapeutic targets.…”

Imbalanced Coagulation in the Airway of Type-2 High Asthma with Comorbid Obesity

“…Compared to lean individuals, adults with obesity exhibit global hypomethylation, with associated increased expression of proinflammatory genes. 106 A study conducted by Nicoletti et al found that surgically-induced weight loss resulted in decreased methylation of IL6 , while an increase in IL6 methylation was observed following weight loss through restricted diet. 107 These authors further demonstrated that baseline SERPINE1 (the gene encoding PAI-1) methylation was significantly associated with percentage of weight loss, suggesting that baseline methylation markers of coagulation pathway-associated genes may predict future weight loss in patients.…”

Adipose Tissue Hypoxia Correlates with Adipokine Hypomethylation and Vascular Dysfunction

“…All images were digitally recorded for post-acquisition analysis using the Automated Edge Detection software system. Relative FMD was calculated using the maximum brachial artery diameter at BSL subtracted from the largest mean values obtained after cuff deflation [%FMD = (RH diameter − BSL diameter / BSL diameter) in mm × 100] as we previously reported [17,[20][21][22][23].…”

“…Resistance arterioles were isolated from adipose tissue samples and cleaned of excess fat and connective tissues. Isolated arterioles were then prepared for measuring the internal diameter in response to changes in intraluminal pressure gradient as we previously described [19,[21][22][23][24]. Briefly, isolated arterioles were cannulated in an organ perfusion chamber using glass micropipettes and a 10-0 nylon Ethilon monofilament suture to secure both ends.…”

“…The generated NO by isolated arterioles was measured as we previously described [19,[21][22][23] using the NO Detection Kit (Enzo Life Sciences, Farmingdale, NY, USA). NO measurements were performed in cannulated arterioles in response to a pressure gradient of ∆60 cm H 2 O. Arterioles under flow were incubated with the NO detection reagents followed by excision, washing, and mounting on microscopic slides.…”